Some medical applications call for constructing a mesh model of an anatomical structure, such as a chamber of a heart.
Lorensen, William E., and Cline, Harvey E., “Marching cubes: a high resolution 3D surface construction algorithm,” ACM SIGGRAPH computer graphics, Vol. 21, No. 4, ACM, 1987, which is incorporated herein by reference, presents an algorithm, called “Marching Cubes,” that creates triangle models of constant density surfaces from 3D medical data.